Method for manufacturing enamel layer and coated article having the same

ABSTRACT

A method for manufacturing enamel layer includes the steps of: a substrate is provided; a spray paint is provided, the spray paint includes liquid fuel and enamel powders; providing a spraying device for spraying the spray paint, the liquid fuel of the spray paint spayed by the spraying device fires to heat and sinter the enamel powder to deposit on the substrate and form the enamel layer. The article manufactured by the method is also provided.

BACKGROUND

1. Technical Field

The exemplary disclosure generally relates to a method for manufacturing an enamel layer and a coated article having the enamel layer.

2. Description of Related Art

Referring to FIG. 1, a current spraying device 100 may be used to form an enamel layer by powder flame spraying use. The spraying device 100 includes an inner pipe 110, a middle pipe 130 surrounding the inner pipe 110, an outer pipe 150 surrounding the middle pipe 130, and a nozzle 170 extending from the outer pipe 150 and bending towards the inner pipe 110. A fuel gas passage 190 is formed between the outer peripheral wall of the inner pipe 110 and the inner peripheral wall of the middle pipe 130. The fuel gas passage 190 is for transmitting fuel gas to the nozzle 170. A compressed gas passage 210 is formed between the outer peripheral wall of the middle pipe 130 and the inner peripheral wall of the outer pipe 150. The compressed gas passage 210 is for transmitting compressed gas to the nozzle 170. Enamel powder for forming the enamel layer is transmitted to the nozzle 170 by the inner pipe 110. Then, the fuel gas flames to heat and sinter the enamel powder. Simultaneously, the sintered enamel powder is atomized into spray particles 230 by the compressed gas to deposit on a metal substrate 250 to form the enamel layer. However, the enamel layer formed by the method is porous. More than 10% of holes formed in the enamel layer are through holes, which reduces the corrosion resistance of the enamel layer. Additionally, because the enamel powder is usually unevenly heated and sintered by the fuel gas, the enamel layer will poorly bond to the metal substrate 250.

Therefore, there is room for improvement within the art.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the embodiments can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the exemplary disclosure. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. Wherever possible, the same reference numbers are used throughout the drawings to refer to the same or like elements of an embodiment.

FIG. 1 is a schematic view of using a current spraying device for manufacturing an enamel layer.

FIG. 2 is a cross-sectional view of an exemplary embodiment of a coated article having another enamel layer.

FIG. 3 is a schematic view of an exemplary embodiment of using a spraying device for manufacturing the enamel layer of FIG. 2.

DETAILED DESCRIPTION

Referring to FIGS. 2 and 3, a method for manufacturing an enamel layer 13 may at least include the following steps:

A substrate 11 is provided. The substrate 11 is made of metal, such as stainless steel, titanium alloy, or nickel-chromium alloy. Alternatively, the substrate 11 may be made of non-metal, such as ceramic.

A spray paint is provided. The spray paint includes enamel powder and liquid fuel, wherein the mass ratio of the enamel powder to the liquid fuel is about 0.75:1 to about 0.85:1. The liquid fuel includes at least one selected from a group consisting of alcohol-based liquid fuel, bio-alcohol oil, and heavy oil. The alcohol-based liquid fuel includes methanol, ethanol, and water, wherein the volume percentage of the methanol is about 80% to about 90%, the volume percentage of the ethanol is about 5% to about 10%, and the volume percentage of the water is about 4% to about 6%. In the embodiment, the liquid fuel further includes a combustion improver, such as potassium chlorate or potassium nitrate.

The diameter of the enamel powder is about 50 nm to about 120 nm. In the embodiment, the enamel powder mainly consists of silicon oxide, aluminium oxide, sodium oxide, and potassium oxide, wherein the mass percentage of the silicon oxide is about 60%-70%, the mass percentage of the aluminum oxide is about 15%-20%, the mass percentage of the sodium oxide is about 4%-6%, and the mass percentage of the potassium oxide is about 4%-6%. The enamel powder may further comprise at least one selected from a group consisting of ferric oxide, calcium oxide, magnesium oxide, and titanium oxide.

A spraying device 20 is provided. The spraying device 20 includes an inner pipe 21, an outer pipe 23 surrounding to the inner pipe 21, a nozzle 25 extending from the outer pipe 23 and bending towards the inner pipe 21, and a gas passage 27. The gas passage 27 is formed between the outer peripheral wall of the inner pipe 21 and the inner peripheral wall of the outer pipe 23, for transmitting compressed gas to the nozzle 25. The inner pipe 21 is made of high temperature resistant asbestos material, such as ceramic. The inside diameter of the inner pipe 21 is about 4.5 mm to about 6.5 mm, which is larger than the inside diameter of the current inner pipe 110 (about 3 mm to about 4 mm) The length of the inner pipe 21 is about 27 cm to about 30 cm, which is longer than the length of current inner pipe 110 (about 15 cm to about 20 cm). As a result, the transmission speed of the spray paint is enhanced and any explosion of the spray paint that may occur in the spraying device 20 is prevented.

The enamel layer 13 is formed on the substrate 11 by spraying. The spray paint is transmitted to the nozzle 25 through the inner pipe 21. The compressed gas is transmitted to the nozzle 25 through the gas passage 27. Then, the liquid fuel of the spray paint transmitted to the nozzle 25 is fired to heat and sinter the enamel powder. Simultaneously, the enamel powder is atomized into spray particles 29 by the compressed gas to deposit on the substrate 11 to form the enamel layer 13. During the spraying process, the spraying amount of the spray paint is about 4 Kg/h to about 9 Kg/h, the spraying rate is about 260 m/s to about 320 m/s. The enamel layer 13 has a porosity of about 0% to about 1%.

In the embodiment, the liquid fuel is uniformly pre-mixed with the enamel powder. When the liquid fuel flames, the liquid fuel uniformly heats and sinters the enamel powder, which enhances the thermal conductivity of the enamel powder, thus the bond between the enamel layer 13 and the substrate 11 is enhanced. Furthermore, for the enamel powder is uniformly sintered, the density of the enamel layer 13 is enhanced and the porosity of the enamel layer 13 is reduced, thus the corrosion resistance of the enamel layer 13 is improved. Additionally, the enamel powders is sintered by liquid fuel, compared to being sintered by gas fuel, the sintered enamel powders have almost no air formed therein, which further reduces the porosity of the enamel layer 13 and enhances the corrosion resistance of the enamel layer 13.

The enamel layer 13 is polished or grinded to smooth the enamel layer 13.

A coated article 10 manufactured by the above method is also provided. The coated article 10 includes a substrate 11 and an enamel layer formed on the substrate 11.

The substrate 11 is made of metal, such as stainless steel, titanium alloy, or nickel-chromium alloy. The substrate 11 can also be made of non-metal, such as ceramic.

The enamel layer 13 has a porosity of about 0 to about 1%. The diameter of holes formed in the enamel layer 13 is about 100 mm to about 1000 mm.

The enamel layer 13 mainly consists of silicon oxide, aluminium oxide, sodium oxide, and potassium oxide, wherein the mass percentage of the silicon oxide is about 60%-70%, the mass percentage of the aluminum oxide is about 15%-20%, the mass percentage of the sodium oxide is about 4%-6%, and the mass percentage of the potassium oxide is about 4%-6%. The enamel layer 13 may further includes at least one selected from a group consisting of ferric oxide, calcium oxide, magnesium oxide, and titanium oxide.

It is to be understood, however, that even through numerous characteristics and advantages of the exemplary disclosure have been set forth in the foregoing description, together with details of the system and function of the disclosure, the disclosure is illustrative only, and changes may be made in detail, especially in the matters of shape, size, and arrangement of parts within the principles of the disclosure to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed. 

What is claimed is:
 1. A method for manufacturing an enamel layer, comprising: providing a substrate; providing a spray paint, the spray paint comprising liquid fuel and enamel powder; providing a spraying device for spraying the spray paint, the liquid fuel of the spray paint spayed by the spraying device firing to heat and sinter the enamel powder to deposit the enamel powder on the substrate and form the enamel layer.
 2. The method as claimed in claim 1, wherein in the spray paint, the mass ratio of the enamel powder to the liquid fuel is about 0.75:1 to about 0.85:1.
 3. The method as claimed in claim 1, wherein the liquid fuel comprises at least one selected from a group consisting of alcohol-based liquid fuel, bio-alcohol oil, and heavy oil.
 4. The method as claimed in claim 3, wherein the alcohol-based liquid fuel comprises methanol, ethanol, and water, wherein the volume percentage of the methanol is about 80% to about 90%, the volume percentage of the ethanol is about 5% to about 10%, and the volume percentage of the water is about 4% to about 6%.
 5. The method as claimed in claim 3, wherein the liquid fuel further comprises a combustion improver.
 6. The method as claimed in claim 1, wherein the enamel powder consists of silicon oxide, aluminium oxide, sodium oxide, and potassium oxide, wherein the mass percentage of the silicon oxide is about 60 to about 70%, the mass percentage of the aluminum oxide is about 15 to about 20%, the mass percentage of the sodium oxide is about 4 to about 6%, and the mass percentage of the potassium oxide is about 4 to about 6%.
 7. The method as claimed in claim 6, wherein the enamel powder further comprises at least one selected from a group consisting of ferric oxide, calcium oxide, magnesium oxide, and titanium oxide.
 8. The method as claimed in claim 1, wherein the diameter of the enamel powder is about 50 nm to about 120 nm.
 9. The method as claimed in claim 1, wherein the spraying device comprises an inner pipe, an outer pipe surrounding to the inner pipe, the inside diameter of the inner pipe is about 4.5 mm to about 6.5 mm.
 10. The method as claimed in claim 9, wherein the length of the inner pipe is about 27 cm to about 30 cm.
 11. The method as claimed in claim 1, wherein during the spraying process, the spraying amount of the spray paint is about 4 Kg/h to about 9 Kg/h, the spraying rate is about 260 m/s to about 320 m/s.
 12. The method as claimed in claim 1, wherein the enamel layer has a porosity of about 0 to about 1%.
 13. A coated article, comprising: a substrate; and an enamel layer formed on the substrate, the enamel layer having a porosity of about 0 to about 1%, the diameter of holes formed in the enamel layer being about 100 mm to about 1000 mm.
 14. The coated article as claimed in claim 13, wherein the enamel layer consists of silicon oxide, aluminium oxide, sodium oxide, and potassium oxide, wherein the mass percentage of the silicon oxide is about 60 to about 70%, the mass percentage of the aluminum oxide is about 15 to about 20%, the mass percentage of the sodium oxide is about 4 to about 6%, and the mass percentage of the potassium oxide is about 4 to about 6%.
 15. The coated article as claimed in claim 14, wherein the enamel layer further comprises at least one selected from a group consisting of ferric oxide, calcium oxide, magnesium oxide, and titanium oxide.
 16. The coated article as claimed in claim 13, wherein the substrate is made of stainless steel, titanium alloy, or nickel-chromium alloy.
 17. The coated article as claimed in claim 13, wherein the substrate is made of ceramic. 